What Size Battery Backup Needed to Keep a G3100 Up and Running?

[PatrickM716]

What we really need is some who has worked this out already to tell us what size (1500VA?) battery backup will be suitable to keep the G3100 up and running for how many hours during a power outage.

I can see that Belkin provided a backup for the AT&T system- it provides 12vdc output instead of 110vac which seems to be a more efficient way to go. Only negative is that it uses only a 12vdc7AH battery and that might only provide 1-2 hours of operation (my guess). 

What would be most useful if some could tell us what the G3100 draws normally from either its 12vdc input (the powersupply is rated at 3.5A) or from the AC into that powersupply.

Someone must have this setup and running?

Thanks,

Patm

[dexman · Accepted solution]

3.5 Amps would be a worst-case scenario. That number can be used in selecting an appropriately sized UPS to sustain it.

This is what I have the Alcatel-Lucent 211 ONT and 3100 router plugged into here at home:

On-Line Double-Conversion UPS System, 120V 1.5kVA 1.35kW | Tripp Lite

Many will say that this UPS is overkill for the ONT & router. That may very well be true.

Now Watts = Volts x Amps... so if I had just the router plugged into the UPS, the power draw would be 120v x 3.5a (max) = 420w.

The chart shows a run time of 24 minutes. Of course, I have the ONT also plugged into the UPS which raises the load. Either way, this UPS will support the ONT & router long enough so that Internet service stays up long enough for users to finish & save their work and shut down.

Two of my three 3200 extenders are supported by smaller Tripp Lite UPSs that provide less run time, but still plenty to save & shut down.

Note: we have not had any protracted power failures since the UPS was purchased. Prior to that, we experienced one that lasted between three and four hours. The old UPS had a weakened battery so the old Tellabs 611 ONT along with the 3100 dropped fairly quickly. Even after a battery replacement, I still went with the larger model.